1. Field of the Invention
The present invention relates to a photographing apparatus and a still image photographing method thereof. More particularly, the present invention relates to a photographing apparatus and a still image photographing method which photographs a still image using an interlace charge-coupled device (CCD).
2. Description of the Related Art
An interlace CCD is mainly used in photographing a motion image to increase the quality of the motion image. In order to photograph a still image using the interlace CCD, a mecha capture method can be used. In the mecha capture method, during the process of reading CCD images of two fields, a signal is accumulated in the CCD only for one field and an iris diaphragm is rapidly closed in the other field to prevent accumulation of a signal in the CCD.
FIGS. 1A and 1B are views for explaining a conventional still image photographing method.
FIG. 1A shows a CCD including a plurality of Mg, G, Cy, and Ye photo sensors, vertical transmission registers 10_1, 10_2, . . . , 10—n−1, and 10—n, and a horizontal transmission register 20 and FIG. 1B shows signals generated when the still image is photographed.
As shown in FIG. 1B, a still image capture signal becomes a high level, after one field, an iris diaphragm is closed. After the iris diaphragm is closed, an XSG1 signal and an XSG2 signal are generated. The XSG1 signal and the XSG2 signal are signals for moving charges accumulated in the photo sensor to the vertical transmission registers 10_1, 10_2, . . . , 10—n−1, and 10—n and are not output simultaneously but are output once in different fields.
If the XSG1 signal is generated, the charges accumulated in horizontal odd lines Mg, G, . . . , Mg, and G, G, Mg, . . . , G, and Mg, . . . , and Mg, G, . . . , Mg, and G are moved to the first vertical transmission registers 10_1, 10_2, . . . , 10—n−1, and 10—n. Further, an electrical image signal of an odd field is output by moving the charges moved to the first vertical transmission registers 10_1, 10_2, . . . , 10—n−1, and 10—n are to the horizontal transmission register.
Further, after one field, as the XSG2 signal is generated, the charges accumulated in horizontal even lines Cy, Ye, . . . , Cy, and Ye, Cy, Ye, . . . , Cy, and Ye, . . . , and Cy, Ye, . . . , Cy, and Ye are moved to the first vertical transmission registers 10_1, 10_2, . . . , 10—n−1, and 10—n. Further, an electrical image signal of an even field is output by moving the charges moved to the first vertical transmission registers 10_1, 10_2, . . . , 10—n−1, and 10—n to the horizontal transmission register 20.
The above-mentioned mecha capture method limits the accumulation time of an image accumulated in the interlace CCD to one field, using an iris diaphragm. In the case in which a still image is photographed using the interlace CCD, an iris diaphragm is inevitably necessary. Further, since the time, at which the iris diaphragm is closed, is changed according to peripheral circuits, the iris diaphragm cannot be minutely regulated, thereby lowering the quality of a still image.